Starter



Sept. 16, 1930. I R. COFFMAN STARTER 051 mm Fil'edgune 8, 192a 2 shoots-Shoot 1 I M Mm I II Q.

16, 1930. R. A. COFFMAN STARTER 2 Shuts-Shoot 2 Original Filed June 8, 1928 tively, on

' device Patented Sept. 16, 1930 BOSCOE A. corrmen, or rrrrsnnnemjrmmsrnvmn STARTER Application filed June 8, 1928, Serial No. 283,858. Renewed August 28, 1920.

This invention aims to provide a starter for internal. combustions engines, and, especially, the engines of airplanes, the starter being capable of mounting in the place of starters now in use, and the starter being so constructed that it may be. very short and still give a large number of turns to an engine shaft with a minimum amount of right line sliding movement inthe actuating piston. It iswithin the province of the disclosure to improve generally and to enhance the utility of devices of that type towhich the invention appertains.

With the above and other objects in view, which will appear as the description proceeds, the invention resides in the combination and arrangement of parts and in the details of construction hereinafter described and claimed, it being understood that changes in the precise embodiment of the invention herein disclosed, may be made within the scope of what is claimed, without departing from the spirit of the invention.

In the accompanying drawings 4 t Figure 1 shows in longitudinal section, a

constructed in accordance with the invention; Figures 2 and 3 are sections taken, respecthe lines 2-2 and 3-3 of Figurel.

The "device comprises a casing or support 1, .of any desired construction, but embodying a cu shaped body or cylinder2, and an annular ead 3 attached by securing elements 4 to one .end of the body 2, the head 3 having a bolting flange 5 which may be so constructed that it will be possible to substitute thestarterhereinafter described for the standard A partition 6 is, heldby the securing elements' 4 between thebody 2 and the. head 3 and carries a sleeve 7 which maybe considered as a fixed part of the casing or support The sleeve 7 extends at one end into the body 2, and at its opposite end within the head 3, as shown clearly in Figure 1. The 1 art of the sleeve 7 that is located within the body 2 has an externalshoulder 8. The sleeve 7 is supplied with an internal spiral rib 9.

e and the rotator 151 Within the sleeve is located a rotatable tubular member'lO which has an. external spiral rib 11 the twist of which is opposite to the twist of the rib 9 of the sleeve 7. 1 At its forward end, the tubular member 10 is provided with a-cufl' 12 mounted to turn about one end portion of the sleeve 7, the cuff ex- .tending backwardly may be made otbronze, the wear plate being disposed against the partition 6 and being bound between the partition and the head 3. I

A cup shaped rotator 15. is mounted to turn inside of the head 3 and about the cufi' 12, in spaced relation to the cuff. The for ward end of the rotatable tubular member 10 abuts against the end'wall of the rotator 15. A ring 18 is threaded or mounted otherwise in the head 3. The rotator 15 turns on ball bearings 16, one set-of the ball bearings being retained by the ring 18. A clutch mechanism 17 forms a driving connection between the cufi -12 of the rotatable member 10 The clutch mechanism '17 has not been described in detail,-.b ecause a person skilled in theart will understand its construction readily, without a description; and because it maybe desirable to use to'a wear'plate 14, which a different kind of a clutch mechanism at the place stated. The end wall of the rotator 16 has an'outstanding. socket 19.

The numeral 20 designates a clutch or equivalent structure whereby the shaft of an internal combustion engine (not shown) may be engagedandturned; The clutch '20- is splinedat 21 into the socket 19 of the rotator 15,for right line slidingmovementon the rotator, and for rotation with the rotator, the rotator being designated by thatname be; cause it is the part bywhich rotation isimparted immediately to the clutch20. .The clutch 20 is secured at 22 to one'end of a hollow piston rod, whichmay be denominated a first piston, slides in the end wallof the rotator 15" and in the adjacent end portion of the tubular member 10. The piston 23 has an external The plston rod 23 member 10. A com re'ssion spring 25 surrounds part of the piston 23, one end of the spring abutting against the shoulder 24, and t e opposite end of the spring finding an abutment against the tubular member 10.

The numeral 26 marks a hollow piston, hereinafter referred to as the second piston, and slidable in the body or cylinder 2. The head 27 of the second piston 26 conforms approximately in shape to the end of the cylinder 2, as Figure 1 will show, and air or other fluid under pressure is admitted between the head 27 of the piston 26 and the end of the cylinder 2 through an inlet 28 mounted in the end of the cylinder.

The head 27 of the piston 26 is reinforced radial fins 29 which extend inwardly to hub 30. Into the base of the hub 30 is threaded 'a driving member 31 of tubular form, the driving member having external spiral ribs 32 and internal spiral ribs 33, the itch of the ribs '32 and 33 being opposite.

he ribs 33 cooperate with the parts 11 of the rotatable tubular member 10, and the ribs 32 cooperate with the parts 9 of the fixed sleeve 7 For convenience of expression, the member 31 may be alluded to as a. part of the second piston 26, and as'being threaded-inone direction on the fixed sleeve 7 of the support 1, and as being threaded in an opposite direction upon the rotatable tubular member 10. A guide 34 is threaded into the outer end of the driving member 31, the piston 23 being slidable in the guide 34, and the guide havinga passage 36 which registers with an opening 37 in the head 27 of the piston 26 to admit fluid pressure upon the piston 23. The numeral 35 designates a compression spring bearing at one end on the shoulder 8 of the sleeve 7, and at its opposite end uponthe fins 29 which are located within the piston 26. The spring 35 is a return spring for the piston 26, and is much stronger than the return spring 25 for the first piston 23.

When fluid pressure is admitted by way of the inlet 28, the piston 23 advances first, because the spring 25 is weaker than the spring 35. When the piston 23 advances, the

driven member or clutch 20 advances, and

couples up with the engine shaft. Then the second piston 26 advances, carrying withit the driving member 31. Rotation is imparted to the driving member 31 and to the piston 26 by the cooperation between the spiral rib 32 of thedriving member 31 and the spiral rib 9 of the fixed sleeve 7. When the driving member 35 is advanced and rotated', as aforesaid, the driving member, in

turn, rotates the'tubular member 10, owing to the cooperationjbetween the spiral rib 33 of the driving member 31 and the spiral rib 11 of the tubular member 10, the general result being that the member 10 will be given many turns, even though the driving member 31'has but a short right 'line movement. This enables the starter to ,be turned out in short and compact form, space and weight being economized, these considerations being highly desirable generally, and especially when the starter is used on an airplane engine.

When the member 10 is rotated, the cuff 12 is turned, and rotation is imparted to the part 15 by wayof the clutch mechanism 17. The splines 21 impart rotation to the driven member 20, and therefrom, rotation is imparted to the engine shaft in the usual way. The clutch 17 is strong enough to afford a driving connection between the cuff 12 and the rotator 15 under working conditions, but the clutch mechanism 17 may be alluded to as a slip clutch, in that if the part 20 and the rotator 15 are reversely turned, in case'of aclosed and claimed means for amplifying the speed of-rotation of the driven means insuch manner that it has a greater speed of rotation than that of the driving means.

I claim 1. In an engine starter, a support, a rotator journaled on the support, means connected to the rotator for engaging an engine shaft, a

rotatable member ]ournaled in the support,

means for connecting the rotatable member with the rotator, a piston slidable in the support, the piston comprising a part threaded in one direction upon the support and threaded in an opposite direction upon the rotatable member, and means for admitting fluid pressure upon the piston.

2. In an engine starter, a support, a rotator journaled on the support, means connected to the rotator for engaging an engine shaft,

a rotatable member journaled in the support,

a slip clutch forming a driving connection between the rotatable member and the rotator,

. a piston slidable in the support, the piston comprising a part threaded in one direction site direction upon'the rotatable member, and

. upon the support and threaded in an oppomeans for admitting fluid pressure upon the piston.

3. In an engine starter, a support, a rotator journaled on the support, means connected to the rotator for engaging an engine shaft, a

rotatable member journaled in the support, means for connecting the rotatable member with the rotator, a piston slidable in the support, the piston comprising a part threaded in one direction upon the support and threaded in an opposite direction upon the rotatable member, means for admittingfluid pressure upon the piston to move the piston in one direction upon its power stroke, and

spring means for moving the piston in an opposite direction upon its return stroke.

4. In an enginestarter, a support, a rotator journaled on the support, a first piston having means for engaging an engine shaft, means for connecting the first piston with the rotator, for rotation therewith and for right line sliding movement thereon, a rotatable member journaled in the support, means for connecting the rotatable member with the rotator,, a second piston slidable in the support, the second piston comprising a part threaded in one direction upon the support and threaded in an opposite direction upon the rotatable member, and means for admitting fluid pressure upon the pistons.

55. In an engine starter, a support, a rotator journaled on the support, a first piston having means for engaging an engine shaft, means for connecting the first piston with the rotator, for rotation therewith and for right line sliding movement thereon, a rotatable member journaled in the support, means for connecting the rotatable member with the rotator, a-second piston slidable in the-support, the second piston comprising a part threaded in one direction upon the sup-port and threaded in an opposite direction upon the rotatable member, means for admitting fluid pressure upon the pistons to move them in one direction upon their power strokes, and a spring means cooperating with each piston to move in an opposite direction upon its return stroke, the spring means for the first piston being weaker than the spring means for the second piston, whereby the first piston will start to move on its power stroke under fluid pressure, before the second piston starts to move on its power stroke, under the same fluid pressure.

In-testimony that I claim the foregoing as my own, I have hereto aflixed my signature.

ROSCOE A. COFFMAN. 

